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Optimal Online Discrepancy in Linear Time

Given online vectors $v_t \in \mathbb{R}^d$ with $\|v_t\|_2 \le 1$, can signs $\varepsilon_t \in \{-1, 1\}$ be chosen in $O(dT)$ total time so that every prefix has $\ell_\infty$ discrepancy $O(\sqrt{\log T})$ with high probability? The previous optimal algorithm ran in time exponential in $T$ and $d$.

Exact FrontierDelta

Prior state unknownproved

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Occurred: Jul 6, 2026

Delta type: SOURCE CLAIM

Assumptions: VibeMathed verification: unreviewed. Publication: preprint. AI contribution: ai-discovered. Imported under CC BY 4.0.

Canonical aliases: Optimal Online Discrepancy in Linear Time · Linear-time discrepancy

Confidence: Not scored

Registry verification: unreviewed · preprint · resolved

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VibeMathed
registry · event recorded by

Ishaq Aden-Ali
human · human collaborator

GPT-5.5 Pro Extended
model · ai model contributor · OpenAI

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This event attributed to Ishaq Aden-Ali

This event attributed to GPT-5.5 Pro Extended

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Optimal Online Discrepancy in Linear Time — Mathematical Frontier Network